A method and apparatus for separation are disclosed in German laid-open patent application specification No. 29 49 230 (having corresponding GB patent application specification No. 2065613A and U.S. Pat. No. 4,439,100.). That apparatus can comprise:
(a) mandrels rotatable relative to one another and introduceable into apertures in the sheet metal elements, the mandrels partly having undercut surfaces for drawing sheet metal elements axially away from one another; or
(b) transverse slides displaceable parallel to one another, one of which having a sloping under surface for lifting sheet metal element(s) remaining in the stack after the last motion phase, so that thereafter another transverse slide can run thereunder before the sheet metal elements to be separated are pushed wholly out of a notional continuation of a guide duct supporting said stack.
In one embodiment, the apparatus is relatively complicated, and can be used only with sheet metal elements having specific apertures. In another embodiment, it is necessary to lift (with application of very considerable force that might deform sheet metal elements) the possibly very high stack at the same time as pressure is being applied by a wedging effect against a side wall of a guide duct containing the stack. Both of those embodiments have disadvantages that should be obviated, if possible.
German laid-open patent application specification No. 26 56 705 discloses apparatus having a slide able to push sideways the lowest sheet metal element of a stack of apertured sheet metal elements, the pushing producing sideways and flat shift of that element. If the slide encounters resistance, the slide can yield downwardly in its wedge-shaped guide. The sheet metal elements slide flat one on another at a separation plane during the entire shift motion. Thus, it is possible for sheet metal elements to become caught at their apertures.